The invention disclosed herein relates generally to apparatus for moving web type recording media past a recording region, and more particularly to a precision paper drive with a rotating pressure pad for use in hard copy recording apparatus.
Hard copy recording apparatus employing a cathode ray tube (CRT) with a fiber optic faceplate for supplying luminous signals and a light sensitive paper web moving past the faceplate is well known. In such apparatus, the fiber optic faceplate is of elongated form and produces luminous signals in the form of minute dots in a linear recording region whose length is the width of the desired record. It is necessary to maintain the recording paper in intimate contact with the recording region of the fiber optic face plate to assure accurately recorded signals. Intimate contact is necessary to properly focus the luminous dots on the paper. Since the depth of field of such an arrangement is in the order of 0.002 inches, the recorded dots become noticeably fuzzy with even small gaps between the paper and the faceplate.
In order to obtain an accurate record, it is also necessary to uniformly and precisely move the paper past the recording region. This, among other things, requires an accurate and precisely controlled drive roller and no slippage between the paper and the drive roller. Thus, it is normal to press the paper against the drive roller with a relatively hard tire.
Conventional paper drive systems in recording apparatus of the above described type have used a stationary foam pressure pad to hold the paper in intimate contact with the faceplate, and a single drive roller/pinch roller pair above the faceplate to pull the paper across the recording region. The geometry of such drive systems necessitates a relatively large border between the end of a paper segment and the beginning of a recorded area.
A large border is undesirable both because it does not fully utilize the light sensitive paper which, in the case of paper capable of producing color images, is relatively expensive, and because a large boarder may not be aesthetically pleasing. Thus, with a conventional paper drive system, if a smaller border is desired, extra trimming steps are necessary.
The applicant has devised a paper drive system which provides for borders of any desired width, thereby avoiding disadvantages of prior art paper drive systems. This paper drive system also insures an accurate record by isolating the paper in contact with the faceplate from fluctuations in paper tension on both the supply and output sides of the recording region.